Add various user- and beatmapset-related sanity checks to submission operations

[bdach]

Not everything is covered yet, just splitting this off as it has grown large enough to PR before continuing further.

What is covered

• user status checks (silences / restrictions)
• required minimum playcount to create a beatmapset
• user upload quota
• online status-related checks (no updating of anything ranked/loved/etc., no updating of anything graved if no quota left to revive)
• beatmap difficulty count limits

What is left to implement (and is coming next / later)

• skipping upload if nothing actually changed
• checking that all online IDs in the .osus are valid
• checking that all the .osus that should be in the package are in it, and that there are no more
• prevent uploading files with potentially harmful extensions
• implementation of beatmap revival start-to-end

Size is not great, but most of it is tests, so I hope I can be forgiven.

[peppy]

All looks pretty good? Really hard to say what's missing or wrong until we have everything in, so let's keep this moving forward 😄